import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: GodK
 * Date: 2024-09-24
 * Time: 12:04
 */
public class Main {
        public static void main(String[] args) {
                Scanner in = new Scanner(System.in);
                int n = in.nextInt();
                char[] ch = in.next().toCharArray();
                int[] hash = new int[26];
                int max = 0;
                char c = '0';
                for (char x : ch) {
                        hash[x - 'a']++;
                        if (hash[x - 'a'] > max) {
                                max = hash[x - 'a'];
                                c = x;
                        }
                }
                if (max > (n + 1) / 2) System.out.print("no");
                else {
                        System.out.println("yes");
                        hash[c - 'a'] -= max;
                        int i = 0;
                        while (max-- > 0) {
                                ch[i] = c;
                                i += 2;
                        }
                        for (int j = 0; j < 26; j++) {
                                while (hash[j] > 0) {
                                        if (i >= n) i = 1;
                                        ch[i] = (char) (j + 'a');
                                        i += 2;
                                        hash[j]--;
                                }
                        }
                        for (int j = 0; j < n; j++) System.out.print(ch[j]);
                }
        }
/*public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String s = " " + in.next();
        char[] ch = s.toCharArray();
        long[][] dp = new long[n + 1][3];

//        long s = 0, h = 0, y = 0;
        for(int i = 1;i <= n;i++){
            dp[i][0] += ch[i] == 's' ? dp[i - 1][0] + 1 : dp[i - 1][0];
            dp[i][1] += ch[i] == 'h' ? dp[i - 1][0] + dp[i - 1][1] : dp[i - 1][1];
            dp[i][2] += ch[i] == 'y' ? dp[i - 1][1] + dp[i - 1][2]: dp[i - 1][2];*/
//             if(ch[i] == 's') s += 1;
//             else if(ch[i] == 'h') h += s;
//             else if(ch[i] == 'y') y += h;
//        }
////        System.out.print(y);
//        System.out.print(dp[n][2]);
//    }
////    public class ListNode {
//        int val;
//        ListNode next = null;
//
//        ListNode(int val) {
//            this.val = val;
//        }
//    }
//    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
//        ListNode cur1 = pHead1;
//        ListNode cur2 = pHead2;
//        int len1 = 0;
//        int len2 = 0;
//        while(cur1 != null){
//            cur1 = cur1.next;
//            len1++;
//        }
//        while(cur2 != null){
//            cur2 = cur1.next;
//            len2++;
//        }
//        if(len1 > len2){
//            int count = len1 - len2;
//            while(count-- > 0){
//                pHead1 = pHead1.next;
//            }
//        }else if(len1 < len2){
//            int count = len2 - len1;
//            while(count-- > 0){
//                pHead2 = pHead2.next;
//            }
//        }
//        while(pHead1 != null){
//            if(pHead1.val == pHead2.val)return pHead1;
//            pHead1 = pHead1.next;
//            pHead2 = pHead2.next;
//        }
//        return null;
//    }
}
